Conventionally, a vehicle equipped with an automatic engine stop-start system is used practically. When an auto stop condition is established while driving, the automatic engine stop-start system automatically stops an engine (an internal combustion engine) of the vehicle. Subsequently when an auto start condition is established, the automatic engine stop-start system restarts the engine so that a fuel efficiency is improved. The automatic engine stop-start system is generally called an idle reduction system, an idle stop system, or, an idle stop-start system.
Japanese Patent No. 4688877 corresponding to US 2007/0267238 A1 discloses a control method in which the engine of the vehicle equipped with the idle stop system is prevented from stopping automatically or starting when a driver is absent.
The inventor of the present application has found the followings. In the vehicle equipped with the idle stop system, there is a possibility that the driver mistakes an auto engine stop state, which is set by the idle stop system, for a manual engine stop state, which is set by an OFF position of an ignition switch.
For example, when the driver waits for a light to change at crossroads, it is not likely that the driver misjudges the engine stop state set by the idle stop system as the engine stop state set by OFF of the ignition switch because the driver continues to drive the vehicle. However, for example, while the driver stops the vehicle at a rotary in front of a station or at a parking space with a parking meter in order to wait for a person, the driver may interrupt the drive of the vehicle for a long time while sitting on a driver seat. In a condition that the driver interrupts the drive of the vehicle for a long time while sitting in the driver seat, a memory of the driver about a cause of the present engine stop state is likely to become obscure. Accordingly, although the engine stop state has been actually set by the idle stop system, the driver may misunderstand and judge that an ignition switch is in an OFF position.
In a case where the driver mistakes the engine stop state by the idle stop system for the engine stop state by an OFF position of an ignition switch, the driver may conduct an operation corresponding to an auto start condition based on his or her misunderstanding that the engine is not going to restart. The operation corresponding to an auto start condition includes, for example, the operation such as that the driver releases a foot brake while setting a shift range to a drive range. In this case, the engine of the vehicle may restart against a driver's intention.